Ries, A. (1996). Focus: The future of your company depends on it. New York: HarperBusiness.
Chicago Style citaatRies, Al. Focus: The Future of Your Company Depends On It. New York: HarperBusiness, 1996.
MLA citatieRies, Al. Focus: The Future of Your Company Depends On It. New York: HarperBusiness, 1996.
Let op: Deze citaties zijn niet altijd 100% accuraat.